Hi Guenter,

> On Mon, Feb 23, 2015 at 05:13:36PM +0100, Lukasz Majewski wrote:
> > Hi Guenter,
> > 
> [ ... ]
> 
> > > 
> > > If devicetree is not configured, of_property_count_elems_of_size
> > > returns -ENOSYS, which is returned, causing the driver to fail
> > > loading.
> > 
> > Has of_property_count_elems_of_size() returns -ENOSYS?
> > 
> > Maybe something has changed, but in my linux-vanila (3.19-rc4)
> > at ./drivers/of/base.c it returns -EINVAL, -ENODATA or number of
> > elements.
> > 
> > Have I missed something?
> > 
> Hi Lukasz,
> 
> Yes, you have. Check include/linux/of.h, line 484, in latest mainline.

Ok. Now I got it.

The above situation shouldn't happen if I put of_find_property() check
on the very beginning of this function (it returns NULL when DT support
is not compiled).

The function would look as follows:

int 
pwm_fan_of_get_cooling_data(struct device *dev, struct pwm_fan_ctx
*ctx) 
{       
        struct device_node *np = dev->of_node;
        int num, i, ret;

        if (!of_find_property(np, "cooling-levels", NULL))
                return 0;

        ret = of_property_count_u32_elems(np, "cooling-levels");
        if (ret <= 0) {
                dev_err(dev, "Wrong data!\n");
                return ret;
        }

        num = ret;
        ctx->pwm_fan_cooling_levels = devm_kzalloc(dev, num *
                                        sizeof(u32), GFP_KERNEL); 
        if (!ctx->pwm_fan_cooling_levels) 
                return -ENOMEM;

        ret = of_property_read_u32_array(np, "cooling-levels",
                                         ctx->pwm_fan_cooling_levels,
                                         num); 
        if (ret) {
                dev_err(dev, "Property 'cooling-levels' cannot be
                        read!\n"); 
                return ret;
        }

        for (i = 0; i < num; i++) {
                if (ctx->pwm_fan_cooling_levels[i] > MAX_PWM) {
                        dev_err(dev, "PWM fan state[%d]:%d > %d\n", i,
                                ctx->pwm_fan_cooling_levels[i],
                                MAX_PWM); 
                        return -EINVAL;
                }
        }

        ctx->pwm_fan_max_state = num - 1;

        return 0;
}

> 
> Guenter



-- 
Best regards,

Lukasz Majewski

Samsung R&D Institute Poland (SRPOL) | Linux Platform Group
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